The proposed work is based upon the observation that a major pathway of taurine synthesis in heart muscle proceeds through cysteamine as an intermediate. The origin of cysteamine appears to be pantetheine and intermediate in CoA synthesis. This pathway through cysteamine seems to couple taurine synthesis to energy production in heart muscle. We propose to study, in heart muscle, the kinetics of the two enzymes, cysteamine oxygenase and pantetheinase, which have key roles in triggering taurine synthesis. Using the isolated working heart model of the rabbit, we will study the interrelationship among the variables; work load, contractility, energy production, substrate utilization (glucose or palmitic acid) and taurine synthesis. BIBLIOGRAPHIC REFERENCES: Read, W.O., Schramm, M.A. and Welty, J.D. Metabolic Pathway of Taurine Synthesis in Heart. In: Taurine, R. Huxtable and A. Barbeau, eds. Raven Press, New York, 1976, pp. 165-168.